The chorda tympani nerve (CT) which innervates fungiform papillae ont he anterior tongue not only transmits information from taste receptor cells to the brain, but appears to be especially important in shaping the morphological and functional development of peripheral and central gustatory structures and in shaping taste-related behaviors. Early removal of the CT drastically alters morphological development of fungiform papillae and behavioral taste preferences in adults. Research proposed here will further characterize these phenomena by identifying the sensitive period for behavioral responses and fungiform papillae structure. Proposed research will also begin to examine the underlying neurobiological substrates of these processes by recording from the remaining gustatory nerves and by studying the terminal field organization of primary afferents in the first central gustatory relay, the nucleus of the solitary tract. These studies will be important in ultimately understanding the role that the chorda tympani plays in instructing development of receptor system development as well as shaping the way other gustatory structures organize. They will also provide information relevant to the formation of specific taste preferences and aversions during development.